Behavior of Post-Tensioned Concrete Girders Subject to Partially Strand Damage and Strengthened by NSM-CFRP Composites

Studies on the flexural behavior of post-tensioned beams subjected to strand damage and strengthened with near-surface mounted (NSM) technique using carbon fiber-reinforced polymer (CFRP) are limited and fail to examine the effect of CFRP laminates on strand strain and strengthening efficiency systematically. Furthermore, a design approach for UPC structures in existing design guidelines for FRP strengthening techniques is lacking. Hence, the behavior of post-tensioned beams strengthened with NSM-CFRP laminates after partial strand damage is investigated in this study. The testing program consists of seven post-tensioned beams strengthened by NSM-CFRP laminates with three partial strand damage ratios (۱۴.۳% symmetrical damage, ۱۴.۳% asymmetric damage, and ۲۸.۶% symmetrical damage). The experimental results showed that the use of CFRP laminates significantly increases the flexural capacity by up to ۱۷.۴ to ۲۰.۴%, corresponding to a strand damage ratio of ۱۴.۳ and ۲۸.۶%, respectively, enhances the stiffness, and reduces strand strain by up to ۱۵.۸ to ۲۲.۲%. However, the flexural stiffness of strengthened beams during serviceability phases is critical as strand damage ratios increase. Additionally, semi-empirical equations were proposed to predict the actual strain of unbonded strands whilst considering the effects of CFRP laminates. The suggested equations provide accurate predictions with little variance. Doi: ۱۰.۲۸۹۹۱/CEJ-۲۰۲۲-۰۸-۰۷-۰۱۳ Full Text: PDF

کلیدواژه ها:

NSM-CFRP Laminates ، Post-Tensioned Concrete ، Strand Damages ، Strengthening.